Human nutrition Flashcards
What should be included in a balanced diet?
- carbohydrates
- proteins
- lipids
- vitamins
- minerals
- water
- dietary fibres
What are the sources, functions and deficiencies of carbohydrates?
- bread, potatos, pasta
- provides energy, fuel for respiration
- lack of energy
What are the sources, functions and deficiencies of proteins?
- fish, meat, nuts
- growth and repair of tissues, makes enzymes
- kwashiokor
What are the sources, functions and deficiencies of lipids?
- butter, oil, seeds
- energy store, insulation, makes cell membranes
- lack of energy, cell membranes not formed
What are the sources, functions and deficiencies of vitimin A?
- eggs, meat, dairy products
- makes chemical in the retina, protects eye
- blindness, bad eyesight
What are the sources, functions and deficiencies of vitimin C?
- citrus fruits, green peppers, tomatoes
- makes connective tissues
- scurvy
What are the sources, functions and deficiencies of vitimin D?
- cheese, butter, fish
- needed for absorption of calcium in bones
- rickets, osteoporosis
What are the sources, functions and deficiencies of mineral calcium?
- dairy products
- strong teeth and bones
- rickets, osteoporosis
What are the sources, functions and deficiencies of mineral irons?
- red meat
- make haemoglobin on red blood cells to carry oxygen
- anaemia
What are the sources, functions and deficiencies of water?
- liquids
- provide medium for chemical reactions to occur
- dehydration
What are the sources, functions and deficiency of dietary fibres?
- wholegrains, cellulose cell walls
- provides roughage for muscles of gut to move food through intestine
- constipation, bowel cancer
How do energy requirements vary?
age
children and teens need more - growing + more active
activity level
more active = more energy
sex
males have more muscle = more energy required
pregnant women
require more energy
breast feeding women
need more energy to produce milk
How does food move through the gut by peristalsis?
circular muscles contract and longitudinal muscles relax above and around bolus -> pushes bolus downwards
Where is bile produced and stored?
produced in liver, stored in gall bladder
What are the functions of bile?
neutralises stomach acid and emulsifies lipids
How is the small intestine adapted for absorption?
- long - 8m
- highly folded - increased SA
- tiny projections called villi - max SA
What does amylase do, where is it made and where does it do stuff
- digests starch into maltose
- made in salivary gland + pancreas
- acts in mouth + small intestine
What does maltase do, where is it made and where does it do stuff
- digests maltose into glucose
- added by small intestine walls
- acts in small intestine
What does pepsin do, where is it made and where does it do stuff
- digests protein into peptides
- acts in stomach
What does trypsin do, where is it made and where does it do stuff
- digests proteins into peptides
- made by pancreas
- acts in small intestine
What does peptidase do, where is it made and where does it do stuff
- digests peptides into amino acids
- added by small intestine walls
- acts in small intestine
What does lipase do, where is it made and where does it do stuff
- digests lipids into fatty acids + glycerol
- made in pancreas
- acts in small intestine
Describe the structure and function of the human alimentary canal
including the: mouth, esophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas
MOUTH
* salivary glands produce saliva - contains salivary amylase
* food bolus (ball) travels to stomach via the oesophagus
OESOPHAGUS
* food moves by peristalsis: the longitudinal muscles relax and circular muscles contract around the bolus
STOMACH
* does the 2 types of digestion
* walls of stomach secrete HCl - kills bacteria + creates acidic environment (pepsin works optimally at pH2)
* food enters duodenum via the sphincter muscle several hrs later
SMALL INTESTINE - DUODENUM
* pancreatic enzymes are released into the duodenum via the pancreatic duct
* bile neutralises HCl (optimum pH for pancreatic enzymes) + emulsifies fat (breaks down to larger SA for lipase to work)
* food passes through small intestine by peristalsis, small intestine walls add enzymes to food
SMALL INTESTINE - ILEUM
* digested food molecules absorbed into blood capillaries in villi
* fat absorbed into the lacteal (part of the lymphatic system)
* blood capillaries join up to form the hepatic protal vein which goes to the liver
* blood then carries food around body to the body cells
* soluble food molecules pass from blood to body cells where its used to build new parts of cells - assimilation
EGESTION - ELIMINATION OF WASTE
* colon absorbs water, leaving semi solid waste (faeces)
* rectum stores faeces
* anus expels faeces
What are the 2 types of digestion and how do they happen?
(and give examples)
- mechanical digestion: food is churned by muscles contracting - eg. chewing (mastication)
- chemical digestion: enzyme pepsin digests protein into peptides (short chains of amino acids) - eg. enzymes
